Dick Tracy's second in command gets tough (7)
I believe the answer is:
richard
'dick' is the definition.
(Dick is a nickname for Richard)
'tracy's second in command gets tough' is the wordplay.
'tracy's second' becomes 'r' (2nd letter of 'tracy').
'in command' becomes 'ic' (military abbreviation).
'gets' says to put letters next to each other.
'tough' becomes 'hard' (synonyms).
'r'+'ic'+'hard'='RICHARD'
(Other definitions for richard that I've seen before include "'Beau' Nash's first name" , "Sir Cliff" , "He died at Bosworth" , "Branson or Cliff" , "Cliff --; -- Wagner" .)